Respuesta :
ANSWER
[tex]\cos(150 \degree) = - \frac{ \sqrt{3} }{2} [/tex]
EXPLANATION
We want to find the exact value of cos(150°).
150° makes an angle of 30° with the positive direction of the x-axis and it is also in the second quadrant.
The cosine ratio is negative in the second quadrant.
Using the unit circle,
[tex] \cos(150 \degree) = - \cos(30 \degree) = - \frac{ \sqrt{3} }{2} [/tex]
Answer:
-√3/2
Step-by-step explanation:
Cos 150° can also be rewritten as shown;
Cos 150° = cos(90°+60°)
According to trigonometry identity
Cos(A+B) = cosAcosB - sinAsinB
Therefore;
Cos(90°+60°) = cos90cos60-sin90sin60
Cos(90°+60°) = 0(1/2) - 1(√3/2)
Cos(90°+60°) = 0-√3/2
Cos(90°+60°) = -√3/2
Cos 150° = -√3/2